Our CDN derives much of its efficiency from files whose checksums don’t change between deploys.
For instance, in a blog, you usually write or update one article in one file, while the rest of the content remains unchanged. In this typical use case, we don’t need to re-upload and re-process these files, since our CDN already has them stored - no checksums have changed except the one file. This also means that your visitors’ browsers don’t need to re-download any files, since they already have …

The topic above doesn’t cover how to do incremental builds using your build tools - it only talks about how to prevent forcing file changes on every build. Some build tools force all files to be unique every build and that is what the topic focuses on changing.

Whether or not the build itself is reprocessing thousands of post will be determined by the site code and the static site generation tools being used.

How is your site being built and does that tool or toolchain support incremental builds? Which static site generator is being used?

If you tell us more about how the site is built, we might be able to suggest ways to do incremental builds with those tools.